We’re also trained to expect a heart attack to happen a certain way: The victim clutches his chest, writhes in pain, and collapses.

But for women, it often doesn’t happen that way.

Study after study shows heart attacks and heart disease are under-diagnosed in women, with the explanation being that they didn’t have symptoms. But research shows that’s not the case.

Women who’ve had heart attacks realize, looking back, that they experienced significant symptoms — they just didn’t recognize them as such.

In a study funded by the National Institutes of Health, and published in Circulation: Journal of the American Heart Association, 95 percent of women (nearly all!) who’d had heart attacks reported experiencing symptoms that were decidedly new or different from their previous experience a month or more before their attacks.

Even when a heart attack is occurring, women are often slow to realize what’s happening and call a doctor, mainly because women’s heart attack symptoms are different than men’s.

This failure to recognize heart attack signs in women has led to a grim statistic: Women are more likely to die from sudden cardiac death than men are, and two thirds of women who have a heart attack don’t recover completely.

To prevent a heart attack from sneaking up on you, watch for these little-known signs of heart attack:

Fatigue.

More than 70 percent of women in the NIH study reported extreme fatigue in the month or months prior to their heart attacks. This was not just your run-of-the-mill tiredness — the kind you can power through — this was an overwhelming fatigue that sidelined them from their usual schedules for a few days at a time.

Sleeplessness or insomnia.

Despite their fatigue, women who’ve had heart attacks remember experiencing unexplained inability to fall asleep or stay asleep during the month before their heart attacks.

Anxiety and stress.

Stress has long been known to up the risk of heart attack. But what women report is the emotional experience; before their heart attacks they felt anxious, stressed, and keyed up, noticeably more than usual.

Moments before or during a heart attack, many women report a feeling they describe as “impending doom;” they’re aware that something’s drastically wrong and they can’t cope, but they’re not sure what’s going on.